Light guide plate, illumination device, and liquid crystal display device

Abstract

A light guide plate ( 11 ) has: a light incidence surface ( 11 c ) through which light from a light source enters the light guide plate; a back surface ( 11 b ) for changing a direction of the light which has entered the light guide plate ( 11 ) through the light incidence surface ( 11 c ); and a light exit surface ( 11 a ). The back surface ( 11 b ) has a plurality of dot holes ( 12 ) each of which has an inclined surface for changing the direction of the light which has entered the light guide plate ( 11 ) through the light incidence surface ( 11 a ), and an angle θ between the inclined surface of each of the plurality of dot holes 12 and the back surface satisfies 53°≦θ≦56°.

1 . A light guide plate, comprising:
 a light incidence surface through which light from a light source enters the light guide plate;   a back surface for changing a direction of the light which has entered the light guide plate through the light incidence surface; and   a light exit surface (i) which faces the back surface and (ii) through which the light whose direction has been changed by the back surface exits,   the back surface having a plurality of dot holes each of which has an inclined surface for changing the direction of the light which has entered the light guide plate through the light incidence surface, and   an angle θ between the inclined surface of each of the plurality of dot holes and the back surface satisfying 53°≦θ≦56°.   
     
     
         2 . The light guide plate according to  claim 1 , wherein the light incidence surface corresponds to a side surface of a rectangular plate whose bottom surface and whose top surface are the back surface and the light exit surface, respectively. 
     
     
         3 . The light guide plate according to  claim 1 , wherein each of the plurality of dot holes is (i) a recess which is made locally so as to protrude inside the light guide plate from the back surface and (ii) has a shape of a cone or a polygonal pyramid. 
     
     
         4 . An illumination device, comprising:
 a light guide plate recited in  claim 1 ;   an optical sheet placed so as to face the light exit surface of the light guide plate; and   a light source provided at the light incidence surface.   
     
     
         5 . A liquid crystal display device, comprising:
 an illumination device recited in  claim 4 ; and   a liquid crystal display panel which receives light from the illumination device serving as a light source.